This invention relates to a process for forming an integral or one-piece axle tube and spindle. Axle-spindle assemblies of this type are useful as so-called full-float axles for trucks and the like.
Truck axles have been formed by welding together an extruded axle tube and a separate spindle of the type which has a central bore and varying wall thicknesses along its length. An example of this type of construction is shown in my prior U.S. Pat. No. 3,837,205 issued Sept. 24, 1974 for a "Process for Cold Forming a Metal Tube with an Inwardly Thickened End".
The process disclosed in U.S. Pat. No. 3,837,205 involves extruding a blank through a tubular die using a punch or ram to force the blank through the die. Extensions or steps formed on the punch produce a thickened end portion on the extruded tube. My more recent U.S. Pat. Nos. 4,277,969 issued July 14, 1981 and 4,301,672 issued Nov. 24, 1981 disclose methods by which ring-like or annular thickened portions are formed within the tube during extrusion of the blank by the movement of the punch through the die.
However, in the past, it has not been feasible to form the spindle of the axle integral with the axle tube in an extrusion type of process such as disclosed in my above-mentioned patents. Axles have been made with integral spindles through forging processes which produce a one-piece unit, but the use of forging is relatively expensive and the metallurgical structures produced are not as desirable as those obtained through my above-mentioned extrusion processes.
Thus, the process of this application relates to the forming of an axle tube through, first an extrusion process and thereafter, a simplified step for converting a portion of the extrusion into an integral spindle, thereby eliminating the prior two-piece welded together, construction and the prior forging systems.